Bone Healing

Question 1

What are the causes of stress and injury?

Answer 1

Hypoxia - lack of oxygen
Ischaemia - lack of blood flow 
Infectious agents 
Physical and chemical agents
Genetic abnormalities
Metabolic alterations
Nutritional imbalance

Question 2

What is hyperplasia?

Answer 2

Increase in cell number

Driven by hormones and growth factors

Question 3

Name and describe the different types of cells

Answer 3

Labile cells = continuously dividing e.g. skin cells
Stable cells = can divide in response to injury
Permanent cells = cardiomyocytes and neurons

Question 4

Describe hypertrophy

Answer 4

Increase in cell size

Question 5

Describe atrophy

Answer 5

Decrease in cell size

Question 6

Describe metaplasia

Answer 6

Reversible replacement of one mature cell type by another

Question 7

Describe morphological changes in cells by necrosis (focus on nucleus changes)

Answer 7

Nuclear pyknosis (dark pinpoint nucleus)
Karyorrhexis (fragmented nucleus)
Karyolysis ( nucleus disappears)
Throughout there is an increase in eosinophilia

Question 8

Define an infarct.

Answer 8

Localized area of tissue necrosis due to cut off of its blood supply

Question 9

Name causes of inflammation

Answer 9

Infections
Trauma and tissue necrosis 
Physical and chemical injury 
Foreign bodies e.g. sutures 
Immune reactions e.g. hypersensitivity, autoimmunity

Question 10

Name the main processes of acute inflammation

Answer 10

Vasodilation
Increased permeability of microvasculature
Emigration of leukocytes
* Review notes for more detail*

Question 11

Name the steps of leukocyte migration

Answer 11

1 - margination 
2 - adhesion and rolling 
3 - diapedesis and transmigration 
4 - chemotaxis 
*** Review notes for details ***

Question 12

What is the function of histamine?

Answer 12

Vasodilation, increased vascular permeability

Question 13

What is the function of prostaglandins?

Answer 13

Fever, pain, vasodilation

Question 14

What is the function of cytokines (TNF, IL-1, IL-6)

Answer 14

Endothelial activation (expression of adhesion molecules), fever

Question 15

What is the function of the complement system?

Answer 15

Chemotaxis

Question 16

Name the different patterns of acute inflammation

Answer 16

Purulent (supprative) inflammation
Serous Inflammation
Fibrinous Inflammation

Question 17

What is an abscess?

Answer 17

A localized collection of pus

Question 18

Name the main cells involved in chronic inflammation

Answer 18

Macrophages, lymphocytes, plasma cells

Question 19

Name the systemic affects of inflammation

Answer 19

Fever
Leukocytosis
Acute phase proteins

Question 20

What can occur in healing?

Answer 20

Either scarring or regeneration

Question 21

Describe the process of healing by fibrosis.

Answer 21

Formation of new capillary vessels (angiogenesis)
Formation of granulation tissue
Maturation then remodeling of fibrous scar (matrix metalloproteinases - MMPs)

Question 22

List factors affecting tissue repair

Answer 22

Wound infection
Diabetes
Nutritional status (protein and vitamin C deficiency decreases collagen synthesis)
Glucocorticoids (decreases collagen synthesis)
Poor blood supply
Mechanical factors (excess movement)
Foreign body in wound